Originally Posted by
FlightDetent
When the weather gets bad enough there will be an RVR value in the TAF, don't worry. Well, that is the point where you actually need to start worrying.
Correct me if I'm wrong, but RVR is only an observation, never a forecast, right? You should not find RVR in any TAF. They might note a trend in the METAR though, eg. R18/0500U or 0500D etc. But as mentioned, that is of limited validity and not a proper forecast.
So I suppose a more complete answer would be;
#1: For non-precision approaches and your (M)DA, use the ceiling and/or vertical visibility predicted in the TAF. For precision approaches, don't even worry about your DA/DH as the RVR will be limiting factor.
#2: Since RVR is not reported in TAF, use the reported visibility for planning. If visibility is forecast as 500m and you need 550m RVR for your CAT1 ILS, you will likely be able to land but for planning purposes the airport is considered below minima and you may need a second alternate for example.
Hope I am pulling all this out of my brain correctly.